HylaFAX hfaxd versions as far back as 4.0pl0 are vulnerable to unauthorized remote access when there are hosts.hfaxd entries without passwords.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/35692/hylafax.txt
Source: https://packetstormsecurity.com/files/35692/hylafax.txt.html